1. Field of the Invention
The invention relates to a video game apparatus and method for displaying images of game, and storage medium storing programs for causing a computer to execute the method, in particular, to a method of displaying the images using a buffer effectively.
2. Description of the Related Art
In recent years, the video games have widely spread to families. Furthermore, the kinds of the games are put on a wide range of types including role playing game, simulation game, fighting game, puzzle game and so on.
Also, there are a wide variety of types of video game apparatuses which are used to play the video games. The video game apparatus may be home-use video game apparatus including a television monitor, or a personal computer/workstation including CRT display device, and the images of games are displayed in the television monitor or the CRT display device. Further, the video game apparatus may also be an arcade video game apparatus which is located at, for example, a game center and which has a body incorporated with a display device.
In the previous video game apparatuses, some display a series of animated images by changing 2D images one after another, and others by using 3D images, which represent images of the video game in perspective and changes the images according to movement of a viewpoint of a player/an object character of the video game (namely, pseudo 3D images). Further, some of these video game apparatuses have the both displaying methods.
The method of displaying the pseudo 3D images brings the video game dynamical effect and the feeling of being at a live performance by representing objects (characters/bodies) in three dimensional style.
Indeed, the method displays the pseudo 3D images by displaying and combining a plurality of polygons models. The surface of each polygon is filled with a pattern and/or shade and then the feel of a material is represented. The pattern and shade may be painted on the polygon by putting a predetermined texture which is a 2D image on the surface of the polygon (namely, texture mapping) or by shading the surface of the polygon based on a pseudo light source which is located in a pseudo 3D space.
Most of the video game apparatuses include a frame buffer which can achieve high speed transmitting of data between the video game apparatus and display device connected to the video game apparatus. Therefore, to display images of games on the display device, the video game apparatus firstly produces data of the image in an area in the frame buffer and secondly transfers the data of the image to the display device.
A first problem is that there is no previous video game apparatus which can display both the 2D image and the pseudo 3D image on the display device. Using only the 2D image, it is not possible to achieve three dimensional effect such as depth (perspective) and movement of a view point. On the other hand, using only pseudo 3D image, it is not possible to represent an expression of a people (an object character of a game) in detail. Therefore, to display both the 2D image and the pseudo 3D image is extremely advantageous in that the both of the images complement each other. The main reason why the representation is not achieved in detail in using the pseudo 3D image is that the previous video game apparatus does not have enough power to process polygon images of high-resolution in real-time.
Herein, an image displayed by the 2D image and the pseudo 3D image is, for example, an image including a close-up image of the upper part of two people and a background image of perspectively represented street. The background image is changed according to a viewpoint of a player/an object character of a game.
Also, in addition to the image data which are supplied to the display device in original aspect, a series of animation images (2D image) or textures (pseudo 3D image), which are used to produce images, may be stored in the frame buffer. In general, the animation images are a series of images which can represent a moving character, but herein, the animation images are also a series of images which can represent changes of display location of the character.
The video game apparatus produces and stores into the frame buffer a plurality of images which are supplied according to transition of story of the video game in order.
In such a case, the storing of the images to the frame buffer is carried out because it is not possible to prepare whole the images before the images are required if data which are used to produce the images are read from a medium of low access speed, such as an external storage device. That is, it is not possible to produce the image at 10 to 60 frames per second, when the required data are read from the external storage device.
When the images are displayed using the method which the images are previously stored in the frame buffer, to display both the 2D image and the pseudo 3D image simultaneously, it is required that both data including the animation images from which the 2D image is configured and data including the textures from which the pseudo 3D image is configured are stored in the frame buffer. This leads to an increase of amount of data which are required at a period of time in a game, and consequently, causes a game device to hesitate more frequently due to rewriting of data in the frame buffer.
In the method which the images are previously stored in the frame buffer, when scene of the game is dramatically changed, for example characters in the game and the background become quite another, as a result, data which are required to produce the new changed image are absent in the frame buffer, it is required that contents in the frame buffer are rewritten to the required data. This rewriting process is to transfer the data from the storage medium or the main memory to the frame buffer. In particular, when the data are transfer from the storage medium to the frame buffer, it takes several seconds to transfer the data. In some case, it takes long time enough to suspend the game.
Especially, in the game having thrilling story or dynamic continuous movement, the suspension of the game dampen the interest of the user and may become a fatal defect. Therefore, the suspension of the game must be avoided at any cost.
However, capacity of the frame buffer is generally about one megabytes to four megabytes and is restricted based on hardware configuration. Therefore, it is not easy to increase the capacity of the frame buffer. Because of this, in general games, the suspensions happen several times or dozens of times from the start of the game to the end of the game due to the rewriting.
The simplest way to avoid the suspensions due to rewriting is to rewrite at the scene which is insensitive to the suspension. Generally, in a game, there are some scenes where the user vacillates this way and that without operations or no updating of the image is required. If the rewriting of the image is executed in such scenes, user seems that the story of the game proceeds without hesitation. However, the technique often depends of nature, contents, story of the game. Therefore, the technique has restriction in that the time points when the rewriting of the image should be executed are limited to some timings.
Another technique to avoid the hesitation is to analyze the story of the game, strictly select the required data in the frame buffer, and partially store the required data (a small amount of data at a time) in an area where the unused data are stored. Thereby, rewrite processes are distributed and it is possible to reduce the probability that user seems that the game suspends. However, in this technique, it should be determined which data in the frame buffer are required for each scene of the game. The determination depends on the pattern of transition of the story of the game, as a result, extremely increases the complexity of the design of the game and the load of the CPU of the game device.
Still another method to avoid the hesitation is to reduce the amount of data in the frame buffer. As a result, the number of rewritings of the frame buffer is reduced or become zero. However, this leads to reduce the number of colors or image pattern. A game using a small number of colors may not have great power of expression, and a game which repeat displaying of the same scenes or the same characters may not supply strong impression to the users. Therefore, these game may not compete on the market in view of development of many types of games.
Thus, aforementioned techniques include fatal defects and the suspension problem due to rewriting of the frame buffer is not resolved essentially.
Therefore, it is an object of the invention to provide a video game device, image display method, and storage medium for simultaneously displaying a 2D image and a pseudo 3D image on a display device.
It is another object of the invention to provide a video game device, image display method, and storage medium which may not require to rewrite data in a frame buffer for a long time without dependency on contents, nature, and story of the game, without increasing complexity of game program and load of CPU, and without reducing power of expression and impression of the game.
According to a first aspect of the invention, there is provided a video game device having a frame buffer which includes a first area storing a first image used in a game, and a game image displaying device which displays the first image to a display device. The video game comprises a game image producing device which produces the first image on the basis of proceedings of the game by combining a 2D image and pseudo 3D image and a game image storing device which stores the first image into the first area. Further, the game image displaying device displays the first image which is produced by the game image producing device and is stored by the game image storing device into the first area, to the display device.
According to the video game device of the invention, it is possible to display the 2D image which may represent a detail expression of a character and the pseudo 3D image which may represent a 3D space in which images are changed according to a viewpoint of the character, to the display device simultaneously.
According to a second aspect of the invention, there is provided another video game device having a frame buffer which includes a first area storing a first image used in a game, and a game image displaying device which displays the first image stored in the first area to a display device. The video game device comprises a second area which is included in the frame buffer and stores second images used to produce the first image, a game image producing device which when the first image includes change parts which change according to passage of time, reproduces the first image by using the second images which correspond to the change parts of the first image, and a game image storing device which stores the reproduced first image into the first area. Furthermore, the game image displaying device displays the reproduced first image to the display device, each of the second images is partial image subdivided in a predetermined size, each of the second images is stored in the second area in consideration of a relationship of an orientation between an image to be stored in the second area and the image to be displayed, and the size, the location, and the orientation of each of the second images to be stored into the second area is optimized so that the interval of accessing to a storage medium other than the frame buffer for producing the first game image is extended.
According to the video game device, it may not require to rewrite data in a frame buffer for a long time without dependency on contents, nature, and story of the game, without increasing complexity of game program and load of CPU, and without reducing power of expression and impression of the game.